1. Field of the Invention
The present invention relates to a probe used for applying a voltage, and to an apparatus for manufacturing an electron source, the apparatus including the probe.
2. Description of the Related Art
Electron-emitting devices included in electron sources are generally classified as being one of two types: thermionic cathode and cold cathode. Examples of cold cathode include field-emission type electron-emitting devices, metal/insulating layer/metal type electron-emitting devices, and surface-conduction type electron-emitting devices.
The operation of a surface-conduction type electron-emitting device is based on a phenomenon wherein electron emission occurs when a current is passed through a thin, small film formed on a substrate, in parallel with the film surface. The basic structure and manufacturing methods of surface-conduction type electron-emitting devices are disclosed in, for example, Japanese Patent Laid-Open Nos. 7-235255 and 8-171849.
A typical surface-conduction type electron-emitting device includes a pair of device electrodes opposed to each other on a substrate, and a conductive film which is connected to the pair of device electrodes and which is provided with a fissure (gap). The fissure (gap) is formed in a part of the conductive film.
A film containing at least one of carbon and a carbon compound as a principal constituent is disposed in the fissure and on the conductive film.
By placing a plurality of such electron-emitting devices on a substrate and by interconnecting the individual electron-emitting devices by wiring, an electron source having a plurality of surface-conduction type electron-emitting devices is manufactured.
By combining the electron source and a phosphor layer, a display panel of an image-forming apparatus is manufactured. Examples of conventional methods for manufacturing such a panel using the electron source will be described below.
In a first example of a manufacturing method, an electron source substrate is fabricated, wherein a plurality of electron-emitting devices formed on a substrate are interconnected by wiring, each device including a conductive film and a pair of device electrodes connected to the conductive film. The entire electron source substrate is placed in a vacuum chamber. After the vacuum chamber is evacuated, a fissure is formed in the conductive film of each device by applying a voltage to each device through an external terminal. A gas containing an organic substance is introduced into the vacuum chamber, and a voltage is applied again through the external terminal to each device in an atmosphere containing the organic substance so that carbon or a carbon compound is deposited in the fissure and on the conductive film.
In a second example of a manufacturing method, an electron source substrate is fabricated, wherein a plurality of electron-emitting devices formed on a substrate are interconnected by wiring, each device including a conductive film and a pair of device electrodes connected to the conductive film. Next, the electron source substrate and another substrate provided with a phosphor layer are joined to each other with a supporting frame therebetween to produce a panel of an image-forming apparatus. Next, the panel is evacuated through a gas outlet of the panel, and a voltage is applied to each device through an external terminal of the panel to form a fissure in the conductive film of each device. A gas containing an organic substance is then introduced into the panel space via the gas outlet of the panel and a voltage is applied again through the external terminal to each device in an atmosphere containing the organic substance so that carbon or a carbon compound is deposited in the fissure and on the conductive film.
In the first manufacturing method described above, as the size of the electron source substrate increases, a larger vacuum chamber and a high vacuum exhauster are required. In the second manufacturing method, it takes a long time to evacuate the panel space and to introduce the gas containing the organic substance into the panel space.
It is an object of the present invention to provide an apparatus for manufacturing an electron source including a voltage-applying probe, in which the probe has improved electrical connectivity and durability, and wherein a reduction in size and facilitation of operations are enabled. It is another object of the present invention to provide a method for manufacturing an electron source, in which cost, and the amount of work and time for manufacturing can be saved, and manufacturing rate improved, thus enabling the method to be suitable for use in mass production of electron sources. It is another object of the present invention to provide an apparatus for manufacturing an electron source having superior electron-emitting characteristics relative to at least some other electron sources. It is a further object of the present invention to provide a method for manufacturing an electron source using the apparatus.
In one aspect of the present invention, a probe is provided for applying a voltage to electrically conductive lines formed on a substrate, the lines being connected to conductors provided on the substrate, the probe includes a conductive sheet, and the conductive sheet includes a mesh sheet in which linear members are woven into a mesh and a conductive material is applied to (coupled to or deposited on) the mesh sheet. An elastic member presses the conductive sheet against the lines, and a holding member holds the conductive sheet and the elastic member together.
Preferably, the holding member includes a block and support plates. Preferably, in the conductive sheet, at least one surface of the mesh sheet is coated with the conductive material. Preferably, the support plates do not cover lower parts of sides of the block, and the elastic member is held separately from the block so as to be independently movable. In accordance with one embodiment of the invention, the conductive material may be applied to (deposited on) the mesh sheet in a striped pattern. Also, the linear members may be woven obliquely with respect to a longitudinal direction in which the electrically conductive lines (wirings) formed on the substrate extend. Preferably, the linear members and the longitudinal direction in which the electrically conductive lines formed on the substrate extend are offset from each other by an angle that is in the range of 10xc2x0 to 80xc2x0. Also, in a preferred embodiment of the invention, surfaces of the mesh sheet are smoothed, the pitch of the individual linear members is smaller than the width of an individual line (wiring), and, more preferably, the pitch of the individual linear members is 300 xcexcm or less.
In another aspect of the present invention, an apparatus for manufacturing an electron source includes a base for supporting a substrate provided with conductors, a gas inlet, a gas outlet, a container for covering a surface of the substrate partially, and a unit for introducing a gas into the container, the unit being connected to the gas inlet. The apparatus also includes a unit for discharging a gas from the container, the unit being connected to the gas outlet, and a unit for applying a voltage to the conductors.
The apparatus of the present embodiment of the invention may include a voltage-applying probe as the unit for applying a voltage to the conductors, the probe including a conductive sheet in contact with at least one electrically conductive line formed on the substrate, and the conductive sheet including a mesh sheet in which linear members are woven into a mesh and a conductive material applied to (coupled to, or deposited on) the mesh sheet. An elastic member of the apparatus presses the conductive sheet against the line, and a block and support plates of the apparatus hold the conductive sheet and the elastic member together, in place. The voltage-applying probe is used for performing an electrical process and for performing testing to detect a disconnection, short-circuit, and resistance of the lines and conductors.
In the apparatus for manufacturing the electron source, preferably, in the conductive sheet, at least one surface of the mesh sheet is coated with the conductive material. Preferably, the support plates do not cover lower parts of sides of the block, and the elastic member is formed separately from the block so as to be independently movable. In accordance with one embodiment of the invention, the conductive material may be applied to the mesh sheet in a striped pattern, and the linear members may be woven obliquely with respect to the longitudinal direction of the electrically conductive lines (wirings) formed on the substrate. Preferably, an angle offsetting the linear members and the longitudinal direction of the lines formed on the substrate is in the range of 10xc2x0 to 80xc2x0. Also, in a preferred embodiment of the invention, surfaces of the mesh sheet are smoothed, and a pitch of the individual linear members is smaller than the width of the individual lines. More preferably, the pitch of the linear members is 300 xcexcm or less.
As described above, in accordance with the present invention, an apparatus for manufacturing and electron source includes a base for supporting a substrate preliminarily provided with conductors and a container for covering the substrate supported by the base. The container covers the surface of the substrate partially, and thus it is possible to form an airtight space on the substrate with the electrically conductive lines (wirings) connected to the conductors formed on the substrate being partially exposed to the environment outside of the container. The container also is provided with a gas inlet and a gas outlet. The inlet and outlet are connected to a unit for introducing a gas into the container and a unit for discharging a gas from the container, respectively. By virtue of these features, the atmosphere inside the container can be controlled to achieve desired conditions. The substrate preliminarily provided with the conductors is a substrate in which electron-emitting sections are formed in the conductors by a predetermined electrical process to produce an electron source. Therefore, the manufacturing apparatus of the present invention further includes a unit for performing the electrical process, for example, a unit for applying a voltage to the conductors. In such a manufacturing apparatus, a reduction in manufacturing apparatus size is achieved. Moreover, operations, such as making an electrical connection to a power source during the electrical process, can be facilitated by the voltage-applying probe as described above, and further there is freedom provided with regard to the design for the size and shape of the container so that introduction of the gas into the container and discharge of the gas from the container can be performed quickly.
In another aspect of the present invention, in a method for manufacturing an electron source, a substrate on which conductors and electrically conductive lines (wirings) connected to the conductors are preliminarily formed is placed on a base, and the conductors on the substrate are covered by a container, although parts of the lines preferably are not so covered. Thus, the conductors are placed in an airtight space formed with the substrate and the container, and the lines formed on the substrate are partially exposed to the environment outside of the container. Next, the atmosphere in the container is controlled to achieve desired conditions, and a predetermined electrical process is performed on the conductors via the parts of the lines exposed to the outside of the container; for example, a voltage is applied to the conductors. The desired atmosphere is, for example, a reduced-pressure atmosphere or an atmosphere in which a predetermined gas is present. The electrical process is a process in which electron-emitting portions are formed in the conductors to produce an electron source (electron-emitting device). The electrical process may be performed a plurality of times in different atmospheres. For example, after the conductors on the substrate are covered by the container, excluding covering parts of the lines, the electrical process is performed in a first atmosphere, and then the electrical process is performed again in a second atmosphere. Desired electron-emitting portions are thereby formed in the conductors and an electron source is produced. Preferably, the first atmosphere is a reduced-pressure atmosphere, and the second atmosphere is an atmosphere in which a gas composed of a carbon compound or the like is present. In the present manufacturing method, electrical connection to a power source, etc., in the electrical process may be facilitated by the use of the voltage-applying probe described above. Since, as described above, there is freedom with regard to the design for the size and shape of the container, etc., introduction of a gas into the container and discharge of a gas from the container can be performed quickly, thereby improving the manufacturing rate as well as improving consistency in the electron emission characteristics of the electron sources manufactured. In particular, uniformity is provided in the electron-emitting characteristics of a manufactured electron source having a plurality of electron-emitting portions. Consequently, in accordance with an aspect of the present invention, it is possible to provide an image-forming apparatus capable of producing images having superior quality relative to those produced by prior art apparatuses.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.